1. Field of the Invention
The present invention concerns the synthesis of soluble forms of melanin and their composition, and methods of using such compositions to provide a naturally-appearing tan to mammalian skin and hair and to provide a sun-screen.
2. BACKGROUND INFORMATION
In biology, melanins are heteropolymers consisting of L-dopa and its enzymatic derivatives. They are ubiquitous in living organisms and are produced throughout the zoological and botanical phyla. In mammalian skin, melanins are produced through enzymatic processes in specialized cells known as "melanocytes". Melanins are the pigments of mammalian skin and hair.
Mammalian melanins are highly insoluble and can be dissolved (solubilized) only through non-physiological treatments such as boiling in strong alkali, or through the use of strong oxidants such as hydrogen peroxide. Tyrosinase, a key enzyme in the melanin biosynthetic pathway, can catalyze the formation of melanin in a test tube using L-tyrosine, L-dopa or 5', 6'-dihydroxyindole as substrates, however, the product is an insoluble precipitate as described above.
It would be of commercial value to have forms of melanin which are soluble at physiological pH and temperature. Such melanins could be applied evenly to mammalian skin and hair in appropriate vehicles without any of the caustic side-effects arising from the harsh reagents needed to solubilize precipitated melanins.
Such solubilized melanins could impart a naturally-appearing tan to mammalian skin and hair. Solubilized melanins would also be effective as sun-screens, since melanins are the chemicals in the skin which absorb ultraviolet radiation and thus provide protection from its harmful effects, such as premature skin aging and the occurrence of skin cancers.